This invention is concerned with disposable diaper adhesive and non-adhesive type closure systems and more particularly to an improved side closure system for disposable diapers comprised of two separate fastening systems, one each of the adhesive and of the nonadhesive type.
Disposable diapers and related articles are well known. A conventional type of diaper system used by both infants and incontinent adults is comprised of an absorbent core encased between a liquid permeable "top sheet" (the user contacting face) and a liquid impermeable "back sheet" (the outer shell portion), which composite encircles the wearer's waist in association with closure systems. These closure systems are most frequently located so that they join front and rear ends or panels of the diaper. These closure systems are most commonly located at either side of the wearer. In order to improve the fit of these diapers and prevent leakage, the side edge portions of the diapers are frequently elasticized which, when the diaper is joined by the side closure systems, provide elasticized leg openings which grip the wearer's thighs.
Conventional diaper closure systems are discussed in U.S. Pat. No. 4,699,622 (Toussant et al.). Toussant et al. was concerned with the problem of diapers shifting on the wearer when used. More specifically, Toussant et al. stated this problem as where
"overlapping front and back waist portions were subjected to forces which tend to cause the front and back waist portion to assume a position relative to each other which is different from the position they assume when a diaper is initially fitted to the wearer."
Toussant et al.'s proposed solution to this problem is a two-point closure system comprised of a conventional type "outer fastening means", which fixes overlapping corners of the front and rear diaper panels to each other. This outer fastening is preferably done with an adhesive fastening tab that will releasably attach to the diaper "backsheet", preferably on a front panel located at the waist engaging portion or area of the diaper. In addition to this outer fastening means, Toussant et al. proposes the use of an "inner fastening means" to prevent shifting of the overlapping corners of the diaper, each with respect to the other, from wearer movement and forces from the elasticized portions of the diaper. Specifically, an inner fastening means is proposed which would resist tensile and peel forces, encountered by the diaper closure system when worn, to prevent separation of the overlapping corner portions. Preferably, the inner fastening means is disclosed as a mechanical type fastener, i.e., a fastener of the type that carries a plurality of projecting members such as hooks which engage with another substrate, such as one that carries loops or fibers into which the projecting members engage. The mechanical fastener is fixed to the corner at the front panel portion of the diaper and is capable of entangling with, e.g., fibrous material typically used as the porous top sheet. The preferred material disclosed is that marketed by 3M Company, St. Paul, MN under the trade name SJ 3492.
A problem with the closure system proposed by Toussant et al., resides in the fact that the outer fastening means contemplated as preferred is a conventional adhesive type closure system comprised of a fastening tab. Most conventional adhesive fastening tabs are used in combination with a release coated tape located on the top sheet of the diaper where the free end of the fastening tab is placed when not in use. When the fastening tab is used, it is removed from the release tape and attached to the front panel of the back sheet of the diaper. The principal problem with this system resides in that these release coated tapes are generally located at one of the most likely areas for the Toussant et al. inner fastening means to attach to the top sheet. This is a problem in that a release coated tape conventionally is a surface treated polyolefin tape resistant to attachment by both conventional adhesives and mechanical fastening means, such as disclosed in Toussant et al. These release coated tapes will therefore seriously interfere with attachment of the Toussant et al. mechanical fastening means to the diaper top sheet, particularly where the mechanical fastening means is of a size and shape on the order of the size and shape of the release coated tape.